The present invention relates to a method for quality assurance of crimp connections produced by a crimping device wherein the crimp connections are produced by placing a crimp connector and an end of an electrical cable between two tool parts that are movable relative to one another and are components of a tool insertable into the crimping device. The quality of the crimp connection is monitored in that measured data, derived from a force-stroke characteristic line measured during the crimping action of the two movable tool parts, are compared to nominal data derived from a nominal force-stroke characteristic line.
The invention also relates to a crimping tool and a crimping device for performing the method.
The method of the aforementioned kind as well as a crimping device with a crimping tool of the aforementioned kind are known from German Patent Application 40 38 658 A1.
For the attachment of plugs to electrical cables with multiple cable wires in an insulating coating the so-called crimping process is usually employed. In a first step, the crimp connector embodied initially as a flat sheet metal part is formed about the cable end by moving two tool parts embodied as plungers relative to one another and is then safely contacted with the cable end. Especially cable harnesses in motor vehicles are comprised of a plurality of different electrical lines which must be provided by crimping with plugs or crimp connectors. The quality assurance of the crimping action is carried out, for example, such that during crimping the force-stroke characteristic line of the tool parts is recorded and directly compared to a nominal force-stroke characteristic line which is stored in the crimping device, or that based on the measured force-stroke characteristic line measured data are processed which are compared to stored nominal data. The nominal data, respectively, the nominal force-stroke characteristic line is determined upon startup of the tool.
In practice, there is the problem that a great number of different cables as well as different crimp connectors are used which require the use of different tools. These tools can be used in a common crimping device and are exchangeable. On the one hand, it is time-consuming and, on the other hand, it is expensive to determine and store after each tool exchange the nominal data which signalize perfect crimping.
It is therefore an object of the present invention to further develop the aforementioned method such that when operating the crimping device with different tools a perfect quality crimp connection can be achieved despite short tool exchange times. Furthermore, the invention has the object to provide a crimping tool of the aforementioned kind for performing the aforementioned method. Moreover, the invention has the object to provide a crimping device for use with such a tool.
The object is solved inventively by providing the tool with an electronic data storage device which stores therein tool-specific nominal data derived from the tool-specific force-stroke characteristic line, wherein these data are respectively compared to the measured data.
By providing the tool with a data storage device which stores tool-specific nominal data and by comparing these nominal data to the measured data, it is no longer required to determine nominal data by complex testing procedures upon tool exchange.
In a preferred embodiment, before removing the tool from the crimping device, data derived from the previously performed crimping processes are stored in the electronic data storage device of the tool.
Preferably, before removing the tool from the crimping device, the number of crimping processes performed during the previous tool use are stored on the data storage device of the tool.
The inventive crimping device comprises an exchangeable tool having an electronic data storage device and a data transmission device for bidirectional transmission of data between the data processing device and the data storage device. Sensors are provided for recording measuring parameters during a crimping process. A data processing device is provided for processing the output signals of the sensors into measured data and for comparing the measured data to nominal data. Upon first start-up of the tool nominal data are stored on the data storage device which nominal data are derived from the force-stroke characteristic line of a perfect crimping process. During the subsequent operation of the device, the measured data are compared to the nominal data stored in the data storage device for quality assurance purposes.
The crimping tool to be used in connection with the crimping device has an electronic data storage device for storing tool-specific data and also has a data transmission device for bidirectional data communication of data stored on the data storage device to and from an external data processing device.